Soil pH in Washington, TX: Lime or Sulfur?

Typical topsoil pH in Washington, TX

Typical topsoil in Washington, TX is pH 7.1, just outside the 6-7 range for vegetable garden. Test first; it may need nothing.

What Washington needs, by plant

• Just outside, test first: lawn (cool-season grass) (off by 0.1), vegetable garden (off by 0.1), roses (off by 0.1).
• Beds or pots instead: tomatoes, potatoes, strawberries, blueberries, azaleas and rhododendrons, blue hydrangeas, pink hydrangeas.

What to do next

If your test lands near 7.1, you can skip lime and sulfur for lawn (cool-season grass), vegetable garden, roses.

How mixed the soil is

Of the 323,389 surveyed acres in Washington, TX, 56% are alkaline (above 7.3), 22% are near neutral (6.5-7.3), 13% are moderately acidic (5.5-6.5), 8% are strongly acidic (below 5.5). Mapped soils run from pH 5 to 8.2, a spread of 3.2 units across 79 soil components. No single class covers 60% of the county, so two gardens a few miles apart here can need opposite treatments. Test your own bed.

Clay, organic matter and rates

Topsoil here averages 31.6% clay and 1.85% organic matter, which this site treats as clay. Moving it one pH unit takes about 11.5 lb of lime or 3.4 lb of sulfur per 100 sq ft. 57% of mapped components carry free carbonate (lime already in the ground), enough that sulfur gets neutralised before it does much.

Washington against the rest of Texas

pH 7.1 is 0.33 below the Texas median of 7.43. 89 of 254 Texas counties have more acidic topsoil. Nationally it is more alkaline than the US county median of 6.05.

Closest in pH within the state: Bee (7.07), Wise (7.08), Caldwell (7.09), DeWitt (7.1), Fannin (7.12), Gaines (7.18), San Saba (7.18), Guadalupe (7.19).

The range in Texas runs from Hardin at 4.64 to Upton at 8.19; Washington sits 69% of the way up.